Balanced slide-valve



(No Model.) 2 Sheets-Sheet 1. G. SELDEN.

BALANCED SLIDE VALVE.

No. 276,721 Patented May 1,1883.

WITNESSES I PETERS. PM hogrlphqr, Wahhiton. m c.

(No Model.) 2 Sheets-Sheet 2.

GQSELDEN.

BALANCED SLIDE VALVE. N0. 276,721. Patented May 1, 1883.

A 1F T e T A a 11 c 21 V I .2 5- I r i M I; i V

' I j l wi l I g 1 g A H A n V 5: l f 2% /r I 1 WA W F-W'ITNIESSES r IJVVEJVTORI' V I Z, Attorney N. PETERS. PhalnLiihognphar. Wnhinginn, D C.

' UNITED STA 5 PATENT OFFICE.

Q GEORGE SELDEN, on ERIE, PENNSYLVANIA.

"BALANCED SLIDE-VALVE.

SPECIFICATION forming part of Letters Patent No. 276,721, dated May 1, 1883.

' Applicationfiled February H, 1883. (No model.)

To all whomtt't may concern Be it known that I, GEORGE SELDEN, of Erie, county of Erie, State of Pennsylvania, have invented a new and useful Improvement in Balanced Slide'Valves,of which the following is a full, clear, and exact description, reference being had to the accompanying draw-' ings, making part of this specification.

My invention relates to the construction of the valve and to the manner of admitting steam to the back of said valve for balancing the same, also .to the manner of equalizing the pressure on the back and face of the valve, and of withdrawing the water of condensation from the valve or steam chest, and will be understood from the following description, with reference to the drawings, in which- Figure 1 represents a vertical section through the valve and steam chest and a portion of the cylinder, taken online 21? w, Fig.2. Fig. 2 isa plan or top view of the valve. Fig. 3 is a vertical section taken in line with the valverod on line 3 y, Fig. 2. Fig. 4 is also a. vertical section taken on a line parallel with the valverod, but at one side thereof; and Fig. 5 is a plan view of the valve-seat, with the steampassages therein indicated in dottedlines.

A represents the valve-seat, having steam ports or passages a and a communicating with the cylinder B and connecting the latter with the steam-chest A. The seat A is also provided with the steam port or chamber 0, with a is to say, with a steam-chamber, e,

which the steam-supply pipe 0' is connected at 0?, and with exhaust ports or chambers'D and D, communicating at D with the exhaustpipe.

E represents the valve, made in hollow or shell form, substantially as represented-that extending from end to end and from side to side of the shell, having openings or ports at e, 0 and e, the first named communicating with the steam port or chamber 0 and the others alternately with the ports or passages a and a. Crossing the shell E in its lower face are two arching bridges, F and F, whichserve as exhaust-passages connecting alternately, one, F,the ports a and D, and the other, F, the ports a and D. These arching bridges extend from side to side of the shell, with their lower ends resting and moving on the valve-seat, and are connected at or near the center of their length' by a pendent U-shapcd loop, E, open on its upper end, and forming a socket extending from end to end of the valve, through which socket the valve-rod G is connected adjustably with the valve by suitable adjusting and jam nuts,

as shown. One side wall, E of the hollow valve E, and by preference the oneIon that side of the steam-chest with which the steam- 6o supply pipe is connected, is made flaring, downwardly, and has a flange orfoot, 71, formed on its lower edge, which is notched or cut away at or near the center ofits length, at h,

to allow the intermittent admission of steam to the chest A at the back of the valve through a small port, 6, in the valve-seat. The notch or opening it in the flange is somewhat less in length than the throw of the valve, and the lips 'or ends it and hof the flange 7i, adjacent to said notch or opening, pass alternately over the port a, cutting off the admission of steam to the valve-chest at eiach end of the throw of the valve, but allowing it to enter between said ends of its throw. The amount of steam 7 thus admitted to theiback ofthe valve through v the port or passagez' in the .valve-seat will be regulated by the size of said port and the length oftimeitremains uncovered,determined by the length of the notch h or the distance between the lips h and if of the flange h.

a J isa small pipe connecting the steam-pipe O with the steam-chest A at the back of the valve, and provided with a cock or valve at J for regulating the admission of steam to said chest. This pipe, with its valve, is desi ned mainly for the admission of steam to the back of the valve for warming it prior to the'starting of the engine, and thereby preventing a too rapid condensation of the steam at the'back of 0 the valve when the valve is first set in motion, such as would destroy the equilibrium and cause the valve to pound on its seat. It is well known to those familiar with the working of this class of valves thatwhen an 5 engineis firststartethwith all parts of the valve cold, the small amountof steam admitted to the back of the valve condenses rapidly and reduces the pressure on the back as compared with that on the lower face of the valve, and I00 the valve is thereby allowed to lift slightly in the effort to restore the equilibrium, and the latter being temporarily restored, the valve drops back again on its seat,thus produciu g the objectionable pounding referred to. This difficultyis obviated by the use of the steam-pipe J in addition to the other means for admitting steam to the valve-chest, and by the admission of steam through said pipe to the back of the valve a sufficient length of time to warm the parts before starting the engine the rapid condensation referred to is prevented. After the engine is well started and in proper running order the supply of steam through the port 6 will be sufficient to maintain the equilibrium, and the valve J may be adjusted for shutting off the supply through the pipe J either wholly or in part, as may be required. Should the pressure on the back of the valve be found insufficient at any time to properly seat the valve, additional steam may be admitted through the pipe J for that purpose.

In order to get rid of the water of condensation in the steam-chest, I connect said chest on its lower side by a small pipe, k, with the exhaust-pipe. This pipe is provided at k with a cock or valve so constructed that while it can be opened widely or to its full capacity it can never be fully closed, thereby adapting it not only to prevent any accumulation of the water of condensation, but also byits adjustment to afford relief to any undue pressure of steam on the back of the valve, and thereby to adjust with precision the balancing of thevalve.

It will be readily understood by those familiar with the operation of balanced slidevalves that in the construction shown and described the principal resistance to the outward or upward thrust of the valve, due to the pressure of the steam on its inner face, is by the counter or downward pressure of the same on the outer or upper faces of the exhaust-arches -F and F, around and over which the steam passes to the ports a and a, and that it is only necessary to allow steam to pass to the back of the valve sufficient to compensate for the difference between the amount of surface upon which such downward or inward pressure is exerted and that upon which the outward or upward pressure is exerted. To admit the steam constantly and freely to the hack of the valve after the cylinder and steamchest are heated up and the condensation is reduced to a minimum would cause too great a pressure, and not only destroy the balance sought to be obtained, but would serve to hold the valve to its seat with a strong frictional grasp, which would impair its free working.

By the construction described the steam is admitted in small quantities andintermittingly tothebackofthevalve,whichinthefirststarting of the engine and while the parts are cold, producing rapid condensation, would be insufficient to hold the valve in balance, as explained. This is remedied bythe direct admission of steam to the steam-chest through the pipe J, to be discontinued whenever the parts are sufficiently heated and in proper balance or condition for working without such extra supply, while by the adjustment of the valve in the pipe Ic, connecting the steam-chest with the exhaust, not only is the water-of condensation drawn on, but any undue pressure on the back of the valve may be relieved and the balancing of the valve regulated as desired.

Additional ports or apertures may be made in the valve-seat for admitting steam to the steam-chest if the single port t is found insufficient; but said port will be found sufficient for ordinary valves.

The valve constructed as described is light, and requires no great accuracy of fitting, ex-

cept on its working-face, and is consequently I economical in construction and not liable to get out of order.

Having described myinvention, whatlclaim as new isq 1. The valve-seat provided with a port or opening through which steam is admitted to the steam-chest at the back of the valve, in combination with a lip or flange on the valve, operating to alternately open and close said port, substantially as described.

2. A steam-chest provided with the port in the valve-seat and with the pipes J and K for admitting steam to said chest at the backof the valve, drawing off the water of condensation, and relieving said valve of undue pressure, in combination with a valve adapted by its vibrations to alternately open and close said port in the valve-seat, substantially as described. 3. The hollow valve or shell E, provided with the transverse arches F and F, forming the exhaust-passages in 'saidvalve, with the pendent open loop E, connecting said arches and forming the socket for the valve-rod, and with the notched flange or lip h, substantially asdescribed. 1

4. The hollow valve or shell E, provided with the transverse arches forming the exhaust-steam passages, the pendent open loop connecting said arches, and the notched flange or lip, in combination with a valvc-seatprovided with a steam-port admitting steam to the back of the valve, and adapted to be alternately opened and closed by the movement of said flange or lip, substantially as described.

In testimony whereof I have hereunto set my hand this 12th day of February,A. D. 1883.

GEO. SELDEN. 

